Studies were performed to examine the human immune response in normal individuals and in patients with congenital and acquired immunodeficiency states associated with a high frequency of cancer. We have focused our current studies on patients with X-linked agammaglobulinemia and isolated growth hormone deficiency (XLA/GHD), X- linked hyper-IgM syndrome (XLM), X-linked lymphoproliferative syndrome (XLP), common variable immunodeficiency disease (CVID) and the Wiskott- Aldrich syndrome (WAS).X-linked agammaglobulinemia and isolated growth hormone deficiency (XLA/GHD) shares many features with the more common X-linked agammaglobulinemia (XLA) or Brutons disease caused by mutations in Brutons tyrosine kinase (Btk). We have shown XLA/GHD to be distinct from XLA since the former patients have no abnormalities in Btk expression including normal catalytic activity. We are currently examining additional X-chromosome genes as the cause of XLA/GHD as they become available as part of the Human Genome Project. We have shown that patients with XLM have markedly reduced cytokine production in response to T-cell activation and that this could be restored with the addition of recombinant CD40L trimer (CD154). These studies suggest the therapeutic possibility of CD154 administration for XLM. These observations are the scientific basis for a new clinical protocol. Recently two other groups cloned the gene responsible for XLP. This gene, termed SH2D1A, has no clearly defined function. We are currently examining the function of this gene. Several studies have suggested a genetic basis for CVID. To gain possible insight into aberrant gene expression, we are using cDNA microarrays to analyze differential gene expression in stimulated CVID and normal B-cells. A recently identified member of the tumor necrosis factor family, termed BLyS, drives B-cell proliferation and immunoglobulin secretion in vitro and in vivo. We are currently negotiating collaboration to examine BLyS and BLyS receptor expression in CVID and the responsiveness of CVID B-cells to BLyS. If CVID B-cells respond to BLyS, it would provide the scientific basis for a new clinical trial. We continue to study the function of the Wiskott- Aldrich syndrome protein (WASp). These studies include demonstration of the expression of WASp in primary human megakaryocytes, platelets and monocytes. Moreover, we have identified two additional WASp-interacting proteins using the yeast two-hybrid system. Finally, using retroviral mediated gene therapy we have corrected the phenotypic abnormalities in Wiskott Aldrich syndrome patients cells. - Immunodeficiency, gene therapy, gene cloning, - Human Subjects & Human Subjects: Minor under 18 Years Old & Human Tissues, Fluids, Cells, etc.